About OpcUa server

[TangDynasty06]

Hello, I would like to use the Milo framework version 0.6.16 to implement an OPC UA server and expose my own data on this server for third-party subscriptions. My data is dynamic and changes frequently. Is implementing an AttributeFilter the best approach to integrate my data? Similar to what's shown in the code location in the diagram below

[kevinherron]

AttributeFilters are best for simple data from sources that you don't need to block while obtaining that data, or where you don't need to do an "optimization" step where data should be read in bulk from the source.

In more complex cases it's best to just implement the AddressSpace::read method yourself, and often to not use the naive SubscriptionModel class to implement the MonitoredItem methods (onDataItemCreated etc...).

[TangDynasty06]

Thank you so much

[TangDynasty06]

I want to implement user authorization, so that only users with read permissions for a node can subscribe to it. I've looked through the source code - to make this work, do I really have to override the createMonitoredItem method in the SubscriptionManager? What's your take - any better suggestions?

[kevinherron]

Install an AttributeFilter on your Nodes and return the appropriate value for the UserAccessLevel attribute based on the Session's user/identity.

[kevinherron]

There's a more complete example of RBAC here: https://github.com/digitalpetri/opc-ua-demo-server/blob/1.0/src/main/java/com/digitalpetri/opcua/server/namespace/demo/AccessControlFilter.java

It's not required to do roles though, you can just do straightforward user-based access with the UserAccessLevel attribute.

[TangDynasty06]

Thank you so much for your help! I really appreciate it.